# What if light passes from lighter to denser medium

• cooper607
In summary: The angle between the reflected ray and the normal is called the incidence angle. The angle at which total internal reflection occurs is the critical angle.

#### cooper607

hello guys,
i need your help to clear my concept on total internal reflection ...when incident ray angle is greater than the critical angle for light passing through denser to lighter medium the total internal reflection occurs...and i know about corresponding snell equation and its validity conditions

now what if i reverse the situation for light passing through lighter to denser medium , then is there any possibility the reflective ray makes 0 degree angle with the normal for a particular incident ray angle??...then what the angle be called ??

and what if the incident ray angle crosses that particular incident ray angle then what will be the consequence of the refection ??
( i know mathematically snell's law says no total internal reflection, but let me know the ultimate consequence of this icident ray )

regards

In such a case it's just normal reflectance from an optical surface. The larger the angle the greater amount of light reflected instead of transmitted. As the angle of incidence approaches 90 degrees you have what's called glancing incidence, in which practically all the light is reflected from almost any smooth surface, regardless of the material. At 90 degrees no light is transmitted, all of it is reflected.

A good estimation of the losses in an optical system is given by : R= (1-n/1+n)2
With n = 1.5 you come up with a value of about 4% loss from light moving from air into glass at normal incidence (0 degree angle)

cooper607 said:
now what if i reverse the situation for light passing through lighter to denser medium , then is there any possibility the reflective ray makes 0 degree angle with the normal for a particular incident ray angle??...then what the angle be called ??
Yes, that "particular" incident angle is zero degrees. Light normal to the surface is reflected back along the normal. Not all light is reflected, though. Some will enter the second medium, along the normal too.

## What happens when light passes from lighter to denser medium?

When light passes from a lighter medium to a denser medium, it will slow down and change direction. This is known as refraction.

## Why does light change direction when passing from lighter to denser medium?

Light changes direction because it travels at different speeds in different mediums. When it passes from a lighter medium (such as air) to a denser medium (such as water), it slows down and bends towards the normal line, which is an imaginary line perpendicular to the surface of the boundary between the two mediums.

## Does the frequency of light change when it passes from lighter to denser medium?

No, the frequency of light remains constant when it passes from one medium to another. However, the wavelength and speed of light may change.

## What happens if light passes from a denser medium to a lighter medium?

When light passes from a denser medium to a lighter medium, it will speed up and change direction. This is known as rarefaction.

## How does the angle of incidence affect the refraction of light passing from lighter to denser medium?

The angle of incidence, which is the angle at which light hits the boundary between two mediums, affects the amount of refraction that occurs. The larger the angle of incidence, the greater the amount of refraction. This is known as Snell's Law.